New 2007 Prius, dead battery

<div class='quotetop'>QUOTE(c4 @ Jan 8 2007, 03:38 PM) [snapback]372636[/snapback]</div>

I noticed about a year after I got my 2004 that the 12 vdc battery was starting to fail. I have heated underground parking at my condo, so when I power up the Auto headlights also turn on. Especially when the coolant pump cycled, the headlights would *really* dim, and the coolant pump made a loud moaning sound.

My commute usually lasts 15 minutes. That first winter, we had a bitter nasty time with routine lows of -40 and highs of -25 C. Without the winter front I was running the defrost on Max Hot and the electric defrost constantly. I think that really took a toll on the 12 v battery.

In December of last year I was gone most of the month on a business trip. I had earlier picked up the VDC battery minders at a great price at auction, so I actually took out the 12 vdc battery, lugged it up to my suite, and left it plugged into the VDC the entire time I was gone. I left the rear seats folded so I'd have an easier time popping the hatch when I returned. The charge light is solid green when charging, blinking green when desulfating. When I left it was solid green.

I had to return one week early due to a family tragedy. When I returned the charge light was blinking. I hooked up the battery, and the alarm immediately went off. Had the fob handy and cancelled it. Then I powered up. The headlights barely flickered when the coolant pump ran, and the pump made hardly any noise at all.

On the wall of my parking stall is a very convenient plugin. I asked the condo association if it was ok to use it, and they had no issues. So I got into the habit of *always* plugging in the VDC battery minder when I had the car parked. An older fellow with a 7-series BMW also uses a battery tender when he is awy in Arizona for the winter.

Taxi fleets that operate the Prius, such as Duffy's Taxi here in Winnipeg, haven't reported any issues with the 12 vdc battery. From what I've seen, they're always in Ready mode. The average city commuter will probably experience issues 2-3 years out, like I did and like you did too.

 

I am one of those with a chronically undercharged 12V. I have had problems for the last 2 years with the car going dead after anywhere from 2 days to a week of no use.

A typical pattern is it's not used for a week and the car needs a jump. I drive 30-45 minutes to work for 5 days and then don't use the car for the weekend. On Monday, the car is dead again. Same thing the next week. Believe me nothing is on, all the doors and hatch are closed, sks off etc. I'm obsessive about it.

After that time, I took it into the dealer convinced that there was something wrong. That afternoon he calls saying nothing is wrong with the car he just charged the battery. When I got there, I pressed because this answer seemed totally outrageous. Why has it died 3x in 3wks?? He said that the 12v loses power & does not charge well if not fully charged (not sure I buy that). The traction battery supposedly charges the the 12v. He says that there is a regulating function that controls charging to protect the traction battery. This limits the amount of charge to the 12v meaning long, long recharge times and probable inability of car to fully recharge 12v on its own. He goes on to tell me that it would be best if I bought a battery charger/jump starter. Truly annoyed, I bought one from pepboys.

Stupid me didn't check it out right then. So this Monday, after 3 days of no use car doesn't start. I say ok get the battery jump/charger. Just one problem, the clamps on the charger are protected by plastic handles. They are too wide to attach to the post!!!!

Furious, I called the Prius roadside service who tell me that I am no longer eligible for program!!!! I convince them to send someone I'll pay. They send a guy who has never jumped a prius and has a battery charger/jump starter with clamps that are too wide to attach to post. They call Toyota to learn how to jump car even though I show the post etc. Toyota tells them I need to run car at 10000 rpm or some such nonsense (how do I know what rpm the engine is running at?) for a certain amount of time to ensure it stays running. Making sure the gas engine started was in fact necessary. Toyota also tells them I should drive around for at least an hour after this rigamorole to make sure the 12v is charged.

I am deeply disappointed that the '07 cars seem to still have this problem. I had thought of trading this one in for a presumably fixed '07. I have to have a reliable car and for the last 2 years I don't have one. I am ordering the battery minder and am ordering a new 12v. But really this has done a lot to convince anyone that knows me that they a prius is not the way to go. I'm not quite ready to give up on it but I'm close.

 

<div class='quotetop'>QUOTE(otterlake @ May 9 2007, 11:07 PM) [snapback]438784[/snapback]</div>

Actually that makes perfect sense. Once a 12 vdc Pb battery is severely discharged, it will usually not accept a full charge unless it has been conditioned. At the very least, you're stuck with a battery you can no longer depend on. I'm not aware of any onboard automotive charging system that can do that.

I've already posted replies to the 12 v battery in similar threads"

http://priuschat.com/index.php?showtopic=27897

http://priuschat.com/index.php?showtopic=30236

I'm in the habit of just leaving the VDC Battery Minder always plugged in at my place, even just overnight. It really has made a big difference.

On something like my new FJ Cruiser, which I only use for driving out to my hobby farm, using a battery tender is even more important. Depending on my work and business travel, the FJ can easily sit for 2 weeks at a time, possibly up to a month. The FJ has a huge battery - compared to a Prius - but the first week I owned it, I had to leave it sitting in the underground parking and it was completely dead when I got to it.

You should also check standby current draw with a good DMM to spot anything unusual. My Prius has a standby of around 29 mA, the FJ around 18 mA. One thing you won't catch is when the Prius decides to purge the brake pressure and run the brake boost pump.

I would like to hook up one of our AEMC power quality analyzers and leave it recording for 24 hours, to catch these weird power draws. I've caught my Prius running the brake boost pump on a couple of occasions, and if it runs say once every 12 hours, after 3-4 weeks the battery is dead anyway.

 

How did the 12V battery get drained the first time, 2 years ago? Once they get drained they're never the same again.

Buy a new one and get on with life.

 

Thanks guys for the replies. I really do need to get on with life I just hope that the new battery does it. The first time was after a week long vacation. I probably left something on that time but I couldn't say now--too much water over the dam. Now I know I'll be much more careful in future!

 

I just got home from a 2 1/2 week trip - Fiona was just fine. I had disabled the SKS, so I used the remote clicker to open the door, climbed in, enabled the SKS. started her up & away we went. I had filled up before I left, and gas went up over 25 cents per gallon while I was gone, but the display shows I'm getting 56 mpg on the current tank (not a lot of miles yet though). I am SO glad to be back in my Prius after 10 days driving a Sienna Minivan (my son's HCH has stick shift which I haven't driven in 20 years) and 8 days driving a non-hybrid Civic. It got so bad I was ready to go to a Toyota dealership just to visit one of Fiona's "cousins"!

 

<div class='quotetop'>QUOTE(otterlake @ May 10 2007, 06:02 PM) [snapback]439537[/snapback]</div>

Also, if you want some more feedback from Prius-tech savvy owners (Wayne, Tony, etc.), the Chicago Prius Group is meeting in just a little over a week on May 20th.
http://www.chicagopriusgroup.com/

For the record, we've had no discharge problem with our 2007 so far. So I would tend to think your problems stem from that intial discharge of the battery you experienced.

 

I've had the same problem with my 2007 Prius - if the car sits for 4 days or more, the 12V battery is drained. I've had to charge the battery at least 8 times. The dealer replaced the battery, though it tested OK. The new battery has now died twice. This is driving me nuts. I've tried several things - making sure that the carpet doesn't get in the way of closing the hatch, firmly closing the hatch, disabling the SmartKey system, and keeping the fob all the way across the house instead of conveniently near the garage - nothing works. If I leave town, I take the truck to the airport, so that I have something that will start when I return! If I didn't have 2 vehicles I'd be in deep. Except for this, I love the car. But this is a big problem.

 

When you drive the Prius, how long are the trips?

If you only use the car for infrequent and short trips, then you may want to consider hooking up a battery minder to keep the 12V battery charged.

 

Yes, I found that 10-15 minute commutes in the middle of winter, especially -30 C and colder, with the lights on, electric defrost on, max heat, etc, would slowly drain the battery

Most modern vehicles have a +100 amp alternator that can do a fairly good job of keeping a battery charged even in short trip use. The Prius charge system for the 12 vdc battery doesn't appear to work very well under short trip scenarios. Taxi fleets have no problem as the car is left in Ready the entire shift

I solved my Prius battery problems by plugging it into the Battery Minder once the car was parked in the garage overnight. My FJ is only driven 1-2 times a week, so I also leave it plugged into a Battery Minder when not in use

 

Along with Patrick and jayman's comments:

Do you lock the car *every* time you park it? That catches most of the common battery-draining boo-boos.

Are there any dealer-installed or aftermarket electronics?

Having been drained multiple times this battery is probably toast also.